A metal–metal bonding process using metallic copper nanoparticles produced by reduction of copper oxide nanoparticles

摘要

Metal–metal bonding was performed using metallic Cu nanoparticles fabricated from CuO nanoparticles. Colloid solutions of CuO nanoparticles were prepared by the reaction of Cu(NO3)2and NaOH in aqueous solution at reaction temperatures (TCuOs) of 20, 40, 60 and 80°C. CuO single crystallites with a size of ca. 10nm were produced, and they formed leaf-like aggregates. The longitudinal and lateral sizes of the aggregates decreased from 522 to 84nm and from 406 to 23nm, respectively, with an increase inTCuO. Colloid solutions of metallic Cu nanoparticles were prepared by reducing the CuO nanoparticles with hydrazine in the presence of cetyltrimethylammonium bromide. The size of the metallic Cu nanoparticles decreased from 92 to 73nm with increasingTCuO. Metallic copper discs were bonded with the metallic Cu nanoparticles by annealing at 400°C and 1.2MPa for 5min in H2gas. The shear strength required to separate the bonded discs increased with increasingTCuO. A maximum shear strength of 39.2MPa was recorded for aTCuOof 80°C.